Soil stockpiles at the Rayonier Mill site in July 2013.
Long-term soil stockpile management work to begin
Rayonier will also soon begin moving soil that they have stockpiled on the site. The soil in the stockpiles is from trenches the city dug on the mill property for their combined sewer overflow (CSO) project.
The soil is currently in 13 mounds that are covered with plastic (see photo). The plastic was a temporary cover that Rayonier used during construction to prevent erosion by wind and rain. However, it would likely not last for several years under harsh weather conditions.
Now, Rayonier needs to arrange the stockpiles for long-term management. Until final site cleanup, the new system will:
- Minimize direct contact with contaminated and potentially contaminated soil.
- Keep wind and rain from eroding the soil by stabilizing it with a grass cover.
- Ensure that rainwater that seeps into the stockpiles doesn’t leave the stockpile area.
Stockpile management plan
Then Rayonier will plant grass seed on the new stockpiles. They will inspect the stockpiles every week until the grass is growing well. Once there is a good grass cover, Rayonier will inspect the stockpiles monthly through the winter, and then every three months to make sure soil is not eroding and that all soil is covered with grass.
Pilot stockpile testing
To find out what general types and levels of contamination are in the stockpiles, Rayonier did some pilot sampling of the existing stockpiles. This very general pilot sampling gave Rayonier and Ecology enough data to develop a plan for managing the stockpiles. Before final site cleanup, Rayonier will develop a plan for fully sampling and cleaning up the stockpiles.
Based on the pilot sampling, most of the stockpiles have some metals and dioxins slightly above the screening levels developed for the upland data summary report. One composite sample found some heavy oil contamination and one found carcinogenic polycyclic aromatic hydrocarbons (cPAHs) above the screening levels.